1. Field of the Invention
The present invention relates to drainage devices for surgical procedures and, more particularly, to a system for improving drainage from a cavity within a human or animal body that breaks up clots or reduces clotting and/or thickening of the fluid to facilitate drainage.
2. Description of the Background
Trauma is the leading cause of death for US civilians under age forty with an incidence of 140,000 deaths per year. Thoracic injuries occur in approximately 60% of polytrauma cases and are a primary or contributing factor in up to 75% of all civilian trauma-related deaths. Ivey, K. M., White, C. E., Wallum, T. E., et al., 2012, “Thoracic Injuries in US Combat Casualties: A 10-Year Review Of Operation Enduring Freedom And Iraqi Freedom,” J Trauma Acute Care Surg, 73(6 Sup 5): S514-S519; Mowery, et al., “Hemothorax and Occult Pneumothorax, Management of,” J. Trauma, February 2011, Vol. 70, No. 2, pp. 510-518. Hemothorax, an accumulation of blood in the pleural space, is a common result of chest trauma. In the U.S. alone, the incidence of trauma-related hemothorax approaches 300,000 cases per year. Mowery et al, supra; see also, Wim G. Boersma, Jos A. Stigt, Hans J. M. Smit., Treatment of Haemothorax, Respir Med. 2010 November, 104(11): 1583-1587.
The primary treatment of hemothorax is tube thoracostomy. Thoracostomy typically involves placement of a large bore (36Fr to 42Fr) catheter (thoracostomy tube or chest tube) for drainage of the pleural space. Mowery et al, supra. Due to the likelihood of a combined pneumothorax, chest tubes for thoracic trauma are typically placed superiorly, as notionally illustrated in FIG. 1. While the majority of traumatic hemothoraces are managed by tube thoracostomy alone, in 3-30% of cases a measurable amount of blood remains in the chest after chest tube placement, a condition known as retained hemothorax, as notionally illustrated in FIG. 2. Kimbrell B J, Yamzon J, Petrone P, Asensio J A, Velmahos G C, Intrapleural Thrombolysis For The Managementof Undrained Traumatic Hemothorax: A Prospective Observational Study., J Trauma 62(5):1175-9 (2007); Rezende Neto J B, Patore Neto M, Hirano E S, Rizoli S, Nascimento Jr B, Fraga G P, Management Of Retained Hemothoraces After Chest Tube Thoracostomy For Trauma. Rev Col Bras Cir. 39(4) (2012); Chou, Lin, and Wu, “Video Assisted Thoracoscopic Surgery for Retained Hemothorax in Blunt Chest Trauma,” Current Opinion in Pulmonary Medicine, Vol. 21, 2015, pp. 393-398.
There are several reasons why a hemothorax may not completely drain—ranging from the sheer volume of blood, the clotting process proceeding more rapidly than the draining process, and patient positioning relative to tube position (i.e., the tube is not in the dependent position). Retained hemothorax (RH) is typically diagnosed via computed tomography (CT) with chest CT imaging often triggered by a finding of persistent x-ray opacity after tube thoracostomy. Empyema, a bacterial or frankly purulent collection in the pleural space, results in 33% percent of RH cases that are visible on x-ray even after chest tube placement (typical RH volume >500 mL). Patients with RH are 12-16 times more likely to develop post-traumatic empyema than those chest trauma patients who do not develop RH. Brims et al., “Empyema Thracis: New Insights Into An Old Disease” European Respiratory Review, Vol. 19, No. 117, pp. 220-228. As such, RH is an independent risk factor for empyema, a condition with a 15-20% mortality rate (higher in immunocomprised patients). RH is also associated with subsequent adverse outcomes such as fibrothorax and trapped lung. While the maximum size of an RH that may be managed without secondary intervention has been debated, correlations between RH size and complications such as empyema and trapped lung have driven current recommendations to administer a secondary therapy (typically surgery) for RH's larger than 500 mL or ⅓ of the hemithorax. Mowery, et al., supra, Boersma et al, supra.
While studies investigating administration of an intrapleural thrombolytic for RH have shown limited success, current recommendations call for early video assisted thorascopic surgery (VATS). 39(4). Chou et al, supra. In VATS, a thoracoscope and surgical instruments are inserted into the chest cavity via 1-3 relatively small incisions. The ipsilateral lung is collapsed to obtain a clearer view of the pleural cavity. Adhesions are then released via blunt digital dissection or sharp endoscopic electrocoagulated dissection and blood and clots are removed by standard suction or a suction-irrigator system. Sponge sticks and ring forceps can enable careful removal of organized collections and some studies have investigated the use of jet-lavage to more efficiently remove adherent clots and membranes without damaging the pleura. Early VATS has been shown to decrease the incidence of empyema and pneumonia and rapidly restore lung function. Chou et al, supra. Compared to previous surgical approaches to RH (i.e. thoracotomy), VATS has been reported to have fewer postoperative complications, less pain, fewer wound and pulmonary complications, shorter recovery time, and shorter length of hospital stay. As a result, VATS has become a preferred primary management option for RH—even over the placement of a second chest tube.
VATS intervention, however, is not without costs and contraindications. Most notably VATS requires a high level of expertise and resources—a skilled thoracic surgeon, an anesthesiologist to perform special intubation and lung drop, as well as significant support staff and equipment. Moreover, the careful removal of coagula adhering to underlying structures with limited visibility usually proves very time consuming and tiresome, and thus, costly work. Tomaselli F, Maier A, Renner H, Smolle-Juttner F M, Thoracoscopical Water Jet Lavage In Coagulated Hemothorax, Eur J Cardiothorac Surg. 23(3):424-5 (2003). In fact, these requirements for specialized equipment and personnel, as well as their associated costs, have been noted as barriers to widespread use of VATS. Milanchi, S., Makey, I., McKenna, R., & Margulies, D. R., “Video-Assisted Thoracoscopic Surgery in the Management of Penetrating And Blunt Thoracic Trauma, Journal of Minimal Access Surgery, 5(3), 63-66. Because it requires single-lung anesthesia, VATS is not only costly and time consuming, but also contraindicated for hemodynamic instability. VATS is also contraindicated for patients with spinal injuries and pulmonary disease or otherwise compromised lung function. Milanchi et al, supra.
It would be preferable to avoid the need for surgical intervention by actively preventing an RH and improving the drainage performance of conventional tube thoracostomy. While attempts at actively clearing the chest tube via Fogarty balloon catheters and other active clearance products have shown some reduction in the amount of retained blood, these devices do little to improve drainage of fluid beyond the distal tip of the chest tube. Boyacioglu, et al., “A New Use of Fogarty Catheter: Chest Tube Clearance,” Heart, Lung and Circulation, Vol. 23, pp. e229-230 (2004); Shiose, et al., “Improved Drainage with Active Chest Tube Clearance,” Interactive Cardiovascular Thoracic Surgery, Vol. 10, No. 5, pp 685-688 (2010).
Additionally, the use of a sterile suction catheter to evacuate the pleural space prior to chest tube insertion has shown modest reduction in duration of tube drainage and need for secondary intervention. Interestingly, a limited recent study demonstrated a lower rate of secondary intervention after prophylactic pleural lavage using warm saline at the time of thoracostomy tube placement and suctioning via a suction catheter advanced into the thoracostomy tube. Kugler, N. W., Carver, T. W., and Paul, J. S., “Prophylactive Pleural Lavage Decreases Secondary Intervention in Patients with Traumatic Hemothorax,” ASCA 39.09; Kugler N W, Carver T W, Milia D J, Paul J S, “Thoracic Irrigation Prevents Retained Hemothorax: A Prospective Propensity Score Matched Analysis,” Presented at Western Trauma Association. Mar. 6, 2016.
Despite an array of successful clinical results most trauma surgeons do not regularly perform thoracic lavage due to real or perceived difficulty and time intensity of the manual procedure, insterility of the procedure, or other reasons. What is needed is a flexible, low-cost and easy-to-use system that enables rapid pleural lavage via the existing chest tube in a completely sterile manner.